As I understand, one of the major weaknesses of the Polish-Lithuanian Commonwealth was that it was a hybrid between a oligarchy and a constitutional monarchy. The szlachta, who sat on the Sejm, effectively called the shots in the Commonwealth, with the king being a elected figurehead, and they were notoriously corrupt, using their power of liberum veto to effectively prevent laws from being passed.
(Please correct me if this assumption is wrong in any way)
So, what would need to happen for the szlachta to be rendered powerless or have hteir power reduced? I know two of the steps include abolishing the liberum veto and having the king be a proper, hereditary monarch, but how can these, among other steps, be accomplished?
A popular idea that just by few different marriages all the problems would be solved is, IMO, more than a little bit optimistic. Look at how the things had been developing elsewhere in Europe. For a monarch to become something more than a celebrated clown, he needed a power base. In other words, there should be a situation in which nobility depends on the royal power. Specifics could vary.
In France this was a long process of increasing the royal domain and getting rid of the old feudal families (especially those who had their titles ‘by God’s grace’) with a lot of “cleansing” happening during the reign of Louis XI, Wars of Religion, reign of Louis XIII. What’s important is that by the end of the100YW kings of France got a solid taxation base allowing them to raise considerable military force independent from the feudal levies. As a result, after Mazarin dealt with Fronde, Louis XIV had his own army that was strong enough to deal with any internal problems and enough of financial power to make
service to him pretty much the only option for a nobility (unless they wanted to remain totally irrelevant), even if they were formally independent from royal power in their landownership. It seems that in most cases an aristocrat could not maintain a required life style based just on an income from his lands: he needed a royal help in the forms of the land grants, paid court positions, income generating properties, etc.
In the Russian state most of the land belonged to the Great Princes/Tsars/early Emperors and a noble was getting the land and serfs only upon the condition of a service and only for as long as a ruler is pleased with his service. Only in mid-XVIII the land possession became permanent but the government still had huge resources for awarding the nobility (short of the profitable marriages, these grants were practically the only way for increase one’s wealth).
In the PLC it was the worst case scenario: from the getgo the land was in the hands of nobility unconditionally and there was never a need or desire to grant a king some financial base that would make him truly independent: the royal estates from which he should finance a staying army were inadequate for the task. So you have to invent a scenario under which either French or Russian model is implemented. Giving the royal clowns extra crowns or even making their rule hereditary would not do the job.